Production of unsaturated compounds



1o temperature of about 400 C. gives rise to vinyl We have now found, however, that PATENT OFFICE- rnonuc'rros or unss'ronsm comomvns John P. Baxter,

England, assignors William A. M. Edwards, and Ramsay Middleton Winter,

tolmperial Norton-on-Tees, Chemical Indus tries a corporation of Great No Drawing. Serial 100.562.190. In

l'.his invention relates to the production of valuable compounds such as acetylene and vinyl chloride from olefine dichlorides of the type of ethylene dichloride or 1.2 dichloro-propane by thermal decomp0siti0n,- and-in particular to the production of acetylene and vinyl chloride from ethylene dichloride.

It is known (Biltz:Berichte 35, 3524 and 3'7,f 2398) that ethylene dichloride on heating to a chloride. this is only an isolated example of the different manners in which a 'dichloro hydrocarbon of the type of ethylene dichloride can undergo thermal decomposition, and that by careful regulation of the reaction conditions, viz. temperature, pressure, time of reaction, nature and amount of diluents, valuable products, such as acetylene and vinyl chloride, may be obtained in good yield. Thus for instance the decomposition of ethylene dichloride to vinyl chloride takes place more readily and with greater freedom fromcarbon deposition if the reaction be eifected in the presence of steam. A similar reaction may .also be brought about in the case of prop lene dichloride, which 'on heating. to temperatures of the order of 400 C.-600 C. yields chloropropylene, ,the reaction againbeing favored by the presence of steam as a diluent. Hydrogen .chloride or inert gases such as nitrogen and carbon dioxide may also be used as'diluents. The reaction is also favored by operating under reduced pressure. I

We have furthermore found that at higher temperatures of the order of 800 C.-900 C. the .decomposition takes place with the formation of a hydrocarbon of the acetylene series. Thus ethylene dichloride gives rise to acetylene and propylene dichloride to allylene. The yield of acetylene hydrocarbons is favored by the presence of diluents such as steam or by working under reduced pressure. p I

According to the present invention, therefore, olefine dichlorides are decomposed by heating to an elevated temperature, preferably above 800 C. and preferably i'nthe presence of an inert diluent, to yield unsaturated hydrocarbons of the acetylene series, or to a substantially lower temperature in the presence of an. inert diluent to yield unsaturated chlorinated hydrocarbons of the type of vinyl chloride. In each case the length of reaction periodis preferably iso chosen that the optimum'yield of desired product may be obtained.

According to a preferred form of the invention ethylene dichloride is heated to a temperature between 800 C. and 1000" C. with steam as a diluent in proportion of at least 8 volumes of steam to 1 of ethylene dichloride vapor with a Appiication September 10, 1931,

Great Britain September 10 Claims. (01. zoo-11o) time of contact varying between 1 to Gseconds depending on the temperature employed. In general, with any given steam ratio a short time of contact afiords a poor yield of acetylene and. some proportion of vinyl chloride, this latter falling-off with increased time of contact and the yield of acetylene rising to a maximum. With too long a period of contact the yield of acetylene also begins to fall owing to carbon formation.

In carrying out the chloride vapor, mixed diluent, is passed through a heated reaction chamber, e. g. a tube, which may be unpacked or packed with inert material such as pumice or with catalytic material. The gaseous products are rapidly cooled and the hydrogen chloride formed by the reaction is absorbed in the water which is condensed. The vinyl chloride may be removed from the residual gas by cooling to C., leaving the acetylene in gaseous form. No polymerization of the acetylene or vinyl chloride is observed when working in this manner. v

The following table illustrate, in the case of ethylene dichloride, the variation of the yields of acetylene and vinyl chloride according to the reaction conditions. Similar behavior is to be expected in the case of other oleflne dichlorides.

invention the oleiine di- Table I Reaction mixtnre:8 volumes of steam 1 volume of ethylene dichloride "D Temperature:- 810' 0.

Contact run of 31% time acetylene chloride Seconds Percent 2. 0 22 52 4.3 41 31 5. l 48 10 pm as 0 Table II- Reaction mistrust-8 volumes of steam 1 volume of ethylene dichloride v m Tempemturoz- 850C.

Yield of toot Yield of acetylene Seconds Emu Pm 0.8 05 00 1.4 2. 6 42 21' 8.4' 60 ll s. 1 41 is if required with the Table III Reaction mlrtunz-S volumes of steam 1 volume oi ethylene oride vapor 'lempanturez- Yield oi Contact Yield of time acetylene m Pawn: Permit 1.0 41 10 1. 7v B3 12 2. l 58 I 15 2. 4 5 3. 0 44 5 8.8 41 5 4. 1 n 5 Table IV Reaction mirturea-ifi volumes oi steam 1 volume oi ethylene di oride vapor 'iemperaturerv Yield oi Contact Yield of time acetylene y;

Second: M Percent Table V vs Temperature:- 1M.

' Yield of Contact Yield oi 1 time acetylene g g Second; Percent O. 0 46 Nil 1.9 cc Nil 8.6 05 Nil 8. 1 65 Nil 13. 1 as Nil Table VI Tom tum-800 O. Cont timor-o seconds Reaction mixture Yield oi Yield oi via 1 Eth lene ace lone Steam a1 0- w ride vapor Volume: Volume Percent Percent 8 1 58 9 4 84 2 l 20 38 l 1 n so As many apparent and widely diflerent embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that we do not limit ourselves to the foregoing examples or description except as indicated in the following claims.

We claim:

1. A process for the production of a hydrocarbon oi. the acetylene series which comprises heating an olefine dichloride to at least substantially 800 C.

2. A process for the production of a hydrocarbon of the acetylene series which comprises heat-,

ing an olefine dichloride to at least substantially 800 C. in the presence of an inert diluent.

3. The process of claim 2 in which the reaction is carried out under reduced pressure.

a. The process of claim 2 in which the inert diluent is steam.

5. The process of claim 2 wherein the volume of inert diluent exceeds that of the oleflne dichloride vapor. D

6. The process of claim 2 wherein ethylene dichloride is treated for from 1 to 6 seconds to produce acetylene.

7. The process of producing acetylene which comprises passing 1 volume of ethylene dichloride vapor together with substantially 8 volumes of steam through a reaction chamber at a temperature of from 800 C. to 1000" C. in from 1 to 6 seconds.

8. The process of producing acetylene which comprises passing 1 volume of ethylene dichloride vapor together with at least substantially 8 volumes of steam through a reaction chamber at a temperature of at least 800 C. and controlling the contact time to obtain a maximum yield of acetylene.

9. A process for the production of unsaturated compounds which comprises heating 1 volume of oleflne dichloride vapor to at least substantially 800 C. in the presence of at least 8 volumes of an inert diluent.

10. The process of producing a hydrocarbon of the acetylene series which comprises passing the vapor of an oleflne dichloride together with at least an equal volume of steam through the reaction chamber at a temperature of at least 800 C. in from'l to 13 seconds.

' JOHN BAX'I'ER.

WIILIAM A. M. EDWARDS. RAMSAY MIDDLETON WINTER. 

